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Dess post wiring and information

There are three wires going to the DESS post

- White/Gray
- Black/Yellow
- Black

The black wire is ground. The other two wires use the black wire as common.

Here is what happens when you put a key on the post. There is a small reed switch in the post that connects to the black/yellow and black wire. The key has a magnet in it, so it closes the reed switch, effectively shorting the black/yellow and black wires together.The key contains an electronic serial number. You program that serial number into memory in the MPEM, so when the key is put on the post, the MPEM reads the serial number, and if it matches one that is stored in its memory, it gives you two beeps and allows the ski to start and run.

This turns on the MPEM. It begins sending out a signal on the White/Gray wire. The center post of the DESS post is connected to the White/Gray wire, and when you put the key on, it makes contact with both the center post and the ring on the post, which is connected to the black wire (ground) This signal "turns on" the key, and it sends the serial number of the key to the MPEM over the White/Gray wire. The MPEM reads this serial number, and if it matches one of the key serial numbers stored in memory, it activates the MPEM which sends out the two beeps. Once this happens, the key circuit is shut off. It no longer has any function, except that the magnet is needed to keep the MPEM alive. The short between Black/Yellow and Black must always be present to keep the ski running.

A lot of times I see recommendations to clean the key, for people that have problem with the ski quitting while running. This is inappropriate advice; cleaning is only recommended if the ski will not start.

The 97's > is known for corrosion problems with the MPEM connectors due to the stupid location they put the MPEM.

The learning key function is not available on the RFI models. It is only available on DI and 4-tec models
White lanyard or float = Learning Key
Yellow lanyard or float = Normal Key

The lanyard and post have a certain OHM value (resistance).
Check your Shop Manual for your year-model.
The MPEM is programmed to accept this value as its "key" If
anything affects this OHM value then the MPEM won't accept
the start command.

MPEM static test
check all connecters for being loose or haveing corrosion.
Include male & female ends and all fuse holders, and ground lugs.
After cleaning, apply di-electrical grease.

locate the rectifier, disconnect the red and yellow wires,
leave the black wire,
then with power hooked to battery, install a new fuse.

- If it pops immediatly, then your mpem is toast,
- If it doesnt pop, then hook-up red wire, if it pops,
then replace rectifier,
- If it pops when yellows are hooked together,
then the problem is in the stator assy.

Do you know there is a 15 amp fuse in the coil box ? This is the main power supply wire to the front of the boat. That power goes to the MPEM, which has it's own set of fuses on it. Did you cover the bases and check all of the fuses ? When testing fuses, just looking at them and saying " they are fine" can get you into looking in the wrong places. Be sure power is coming off each side of the plugged-in fuse. It is possible to have a bad fuse holder, especially the ones in the coil boxes. Use a pointed test light on each side of the fuse. Main power fuses are 15 amp. The 5 amp fuse protects the MPEM, and the 7.5 amp fuse protects the system from the VTS. So, to get spark, you must have a good 5 amp and two good 15 amp fuses, plus all good grounds and connectors that make good contact, a working DESS switch, and the mag connector connected.
Once you prove all of that is good, you can start looking for bad components.
When you first press the start button one time, even without the lanyard connected, the dash should come alive. If the gas guage is working, it will show bars on the guage, if not, it will show a red idiot light. The oil tank idiot light will also come on. If the VTS is good, it will go up and down when you push the VTS switches. If you have an info center guage, it will come on too. But without the lanyard attached and the code in it read by the mpem, you will not have a working starter switch that sends power to the starter relay, nor will the ignition be activated. The key contains an electronic serial number. You program that serial number into memory in the MPEM, so when the key is put on the post, the MPEM reads the serial number, and if it matches one that is stored in its memory, it gives you two beeps and allows the ski to start and run.

I have a 97 Sea Doo Sportster. It does not go beep-beep anymore, but I can hear something clic twice. What is the physical location of the DESS beeper? I think the two clics are in the box behind the seat in the engine compartment

so am i right in thinking without the correct lanyard (ive recently replaced the mpem and need to get a dealer to program the lanyard in) i wont get any beeps at all or diagnostic codes when pressing the start button 5 times? its a 96 xp if that makes a difference. i dont want to take it to the dealer and pay for coding if there is other problems causing it to do nothing at all

Yes. The MPEM must recognise a key's code that is emmbeded, and the code placed in one of the mpem's seven available slots. You will have to get your DESS key programed into the MPEM for the mpem to begin functioning.

I know this is an old thread but you guys give out so much useful information. I have a 96 XP that I purchased with a cracked jug. I am pretty mechanical so rebuilding it was a piece of cake (although tighter than a snowmobile). Anyway, to get the two beeps I have to press the start button twice, then put the DESS on, then I will get two beeps. If I just put it on it won't beep/start/do anything really. Can you help me?

I have 1996 Seedoo spx, I ordered a new DESS post for the Seedoo and when it arrived it had four wires(black, black/yellow, black/purple and white) vs three (black, black/yellow and white), according to the site the part number is the updated replecement for the old part number. Is there a wiring diagram for wiring in the new post? I assume the additional wire is for a new style MPEM. Any help would be great

Manual Programming

Originally Posted by Coastiejoe

r10kbs,
As mentioned, you will need to get your keys programed for your ski. This is designed so that others cannot start (steal) your ski...

As a locksmith I know that automotive vehicles can often have their transponder keys programmed using the vehicle itself, often that requires 1 or 2 existing original keys that are used in a series of steps that vary based on the vehicle manufacturer. Does the Sea-Doo (2002 GTX 4-TEC) have that capability or is the only option paying to have it programmed in by a shop?

As a locksmith I know that automotive vehicles can often have their transponder keys programmed using the vehicle itself, often that requires 1 or 2 existing original keys that are used in a series of steps that vary based on the vehicle manufacturer. Does the Sea-Doo (2002 GTX 4-TEC) have that capability or is the only option paying to have it programmed in by a shop?

I do not think that is the case with skis. In the automotive field, you are NUTS of you don't get a third key when you have the vehicle as in MOST cases it requires having two keys to self program a third key. So,,, if you lose one, you are forced to go tot the dealer or a lock smith and pay the price for labor, programing, and the key. If you have two keys, you can do it all yourself and have a local Lowes or Home Depot cut the key..

I know this is an old thread but you guys give out so much useful information. I have a 96 XP that I purchased with a cracked jug. I am pretty mechanical so rebuilding it was a piece of cake (although tighter than a snowmobile). Anyway, to get the two beeps I have to press the start button twice, then put the DESS on, then I will get two beeps. If I just put it on it won't beep/start/do anything really. Can you help me?

I have read that some of the Skis required to be "Woke UP" before they will recognize the lanyard. To do so, you must press the start/stop button. I own two late model skis and one will recognize the lanyard instantly and the other you must press the start/stop button. One year apart in my case..

I have 1996 Seedoo spx, I ordered a new DESS post for the Seedoo and when it arrived it had four wires(black, black/yellow, black/purple and white) vs three (black, black/yellow and white), according to the site the part number is the updated replecement for the old part number. Is there a wiring diagram for wiring in the new post? I assume the additional wire is for a new style MPEM. Any help would be great

Your E-box has that extra wire capped for future DESS connection. Look at a '96 GTI or HX wire diagram, same MPEM, but these have DESS stock, Hope this helps!

You may need the e-box harness wire, If your new post does not reach/have the watertite rubber grommet.
I'm sure Minnetonka4me (a member re-seller) could sell you an inexpensive used one.